Radio receiving system



Oct, .16, 1928.

E'. W. Kl-:LLoGca4 RADIO RECEIVING SYSTEM Filed Nov. 21. 19,23

' CoupIng Tube For ,Antennafl etl Variable Coupling Cfr. Fr- 'I I Ant ennafz. A Sst'l n IU TI T T 0t.1s,192s. I v1,687,570

E. w. KELLOGGA A RADIO RECEIVING SYSTEM Filed Nov. 21. 1922 5 sheets-sheet 3 Inventor: l

Edward w. Kellogg,- I

- His Attorney.

Oca 16, 192& 1. 1,687,570

' E. W.,KELLO.GG l

RADIQRECEIVING SYSTEM v Filed Nov. 21. 1922' 5 sheets-sheet 4 @2V ,A PIE. mmf@ @d WMM JM @s ...ma H m, m ,w Ekvw Mw m ,M2 M3, Mm UW m. All M. QNWLWRUVA'WnNuVkw* ocr, 1s, 192s. 1,687,570'

E. W. KELLOGG fumo nEcEIvING SYSTEM Filed Nov. 21. 1922 5 sheets-sheet" 5 HiSALLor-n.

Patented oct. 16, 192s.

UNITED STATES PATENT- oFFlc-E.

EDWARD w. xELLoeG, or scHnNncTADY, NEW Yonx, nssrenon 'ro GENERAL unc- 'rnrc confirm, a conronarron or Naw Yonx.-

RADIO RECEIVING SYSTEM.

Application led November 21, 1922. Serial No. 602,458.'

f tems for obtaining -a lhigh degree of selectivity in reception. i

Y For the purpose 4of eliminating interference from stations and static it is now recognized that highly directive antennae are espe-l cially eiective. While sharply directive receiving antennae have been constructed em-4 ploying a single loop, a combination of two loops or of a loop and a vertical antenna and a long horizontal antenna ofthe type now i known in the art as the wave antenna, it is found in practice that there isa limit to the directivity which may economically be ob tained with any of these arrangements.

One of the objects of my invention is to provide a receiving system made up'of a plurality of receiving units whlch are connected to one another and to a Areceiving station in such a-way that sharper directivity 1n reception may be obtained than can be obtained withpreviously employed systems.

Another object of my invention is to provide a maximum of directivity with a minimum number of units. A

Still` another object of my invention is to provide a receiving system which will-permitV of highly directive reception upon a single antenna system from a plurality of transmitting stations located in directions between which there may bea considerable angle.

In carrying my inventioninto eiect I may to advantage employ a plurality of wave antennae of the type described inBeverage Patent 1,381,089, JuneF 7 1921, althoughother forms of -directive antenna units may be4 employed as will appear from the description which follows. It is well know that if a' wave antenna is sol constructgd thL vv,the current flows therein at a vecity equal tot-the velocity of light the maximum signal reception will be in the direction of the antenna.

By suitably loading a wave antenna by se? ries condensers or shunt'inductances or both the eli'ective wave velocityof the antenna can the same` directive curve as an` 1n If a signal comes from an angle 0 to the directlon 'of the antenna the point of maximum lnduced electromotive force moves alongthe Y v antenna with a veloclty m and for max1- mumsignal the wave velocity on'the antenna shuld also equal co7; 0. I f it is desiredto receiveJvv signals from a direction at right angles to theantenna this condition requires a line of infinite wave velocity. Reception obtained in'this manner either by means of a wave antenna or by, equivalent means I term broadside reception, while reception from the tdirection of the antenna I term end on recep- The wave antenna when employed either as an end on or a broadside receiver may be considered as'made up of an infinite number of receiving elements of infinitesimal size,

which in the case of waves coming from the.

direction of the desired signals deliver the energy which they collect, in such phase at the receiver as to give full vamplitude addition. This tine subdivision and distribution lof energycollecting elements however is not essential, as a. comparatively small number of `larger unitsv properly spaced will give substantally the same directive properties. ForA example, a. row of four antennae spaced-a quarter wave length apart gives practically finite number of small antennae distributed over-a wave length. -The number of units multiplied by Y the spacing gives the length ofthe equivalentv wave antennae and the equivalence is very close provided the spacing does not exceed a quarter wave length in the case ofan end 4on Vunits whethereach of them is itself directive or not permits however, of greater iexibility.v

in the adjustment of the` receiving system for reception from different, directions.l l

The novel features which I -believe `to be characteristic of my invention are set forth with particularity lin the appended claims. My invention itselfhowever both as to its or? ganization and method of operation to ther with the manner in'l which the various o jects thereof may be obtained will best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 is a diagrammatic representation of a complete receiving system adapted for multiplex reception; Fig. 2 shows a slight modification in the receiving system; Figs. 3 and 6 to 9 inclusive are illustrative diagrams of multiple unit combinations; and Figs. 4, 5 and 10 are directive curves illustrative of some of the capabilities of my invention.

The methods to be employed in utilizing a row or group of separate antenna units Will depend upon the type of units and their arrangement with respect to the direction or directions from which signals are to be received. In general, to obtain the greatest flexibility of operation, a. separate balanced metallic transmission line would preferably be employed for transmitting the energy received by each unit to the receiving station, although in some cases a single transmission line may be used for several antennae.

At the receiving station means should be provided for combining the signals received from the several units in a single circuit4 either by a magnetic coupling between each of the transmission lines and t-he combining circuit or by some equivalent means. Provision should also preferably be made for adjusting both the phase and intensity of the signals from each antenna as they are impressed upon the combining circuit. Phase adjustments may be made by off tuning, by means of a rotating magnetic field provided by a. split phase circuit or by means of artificial transmission lines ot variable length.l

The last mentioned method has the advantage that in most systems the same adjustment is correct for all Wave lengths or at leastfor a considerable band of wave lengths providing the proper polarity of transformers is observed. In some cases the desired phase adjustment may be obtained by proper proporlioning of the lengths of the transmission mes.

In any multiple unit receiving system or in any receiving system in which Signal frequency currents are transmitted for considerable distances care will be needed to prevent undesired eleetromotive forces or currents from entering and preventing the svstem from functioning as intended. The following are some of the precautions which may be found desirable,-

l. Electrostatic shielding between primaries and secondaries of transformers,- particularly of transformers used to connect transmission lines to antennae.

2. The use of iron core transformers or of astatic air core transformers to reduce undesired magnetic couplings.

3. Careful balancing and transposition of transmission lines and balancing of all transformers or coils connected thereto which have connections to neutral points of their wind-` lugs.

4. Damping of transmission lines by resistance to prevent reflections and, standing wave eEect-s.

5. Fitting of impedances between transmission linrs and artificial lines or other apparatus to which the transmission lines are connected.

6. Prevention of excessive voltages building up on transmision lines by wave antenna action. This may involve draining 0H' of foreign currents from the neutral points of drain coils or of balanced transformer wind- `ings, or the loading or sectionalizing of the transmission lines in such a way as to reduce their action as antennae without materially impa-iring their efciency as transmissionV static antennae spaced a distance apart provided I is less than a quarter wave length,

each antenna being connected tothe receiving st-ation by a transmission line and .the lengths of these lines diii'ering in electr1cal length progressively by a distance Similarly a broadside innite velocity wave antenna of length L mightbe replaced by a row of n static antennae separatedby a distance L/u, provided L/n does not exceed a. half wave length. The transmission lines in this case should all have the same electrical length. In case it is not convenient to build lines having a geographical lengt-h corresponding to the desired electrical length the electrical length may be made greater or less than the geographical length by suitable loading or by the addition of a suitable artificial line. It' all-0f the antennae in the row or group were static antennae which receive equally from all directions the system would have a certain directivecurve, characteristic of the location and spacing of the units, the .wave length rel ceived, and the electrical length of the transmission lines. We may callthis the group directive curve and designate it by A. If now the static antennae are replaced by antennae which individually have a directive curve B, then the system as whole will come where curve B taken by itself wouldA give undesirabler reception, and vice versa, a

product curve may be obtained with a number of blind spots and with very slightl reception ovr a wide ran e of direction.

The theory of the pro uct principle may be illustrated by the case of two loop-and-vertical, cardioid units, placed a half wave length apart, and equally distant from the source of the desired signal and connected to the receiving station by transmission lines of equal length, as indicated in Fig. 3. First to ind curve A, we determine thev kdirective 'properties for two static antennae'placed as described. For 0:0, or the direction of the desired signal, the space wave strikes the two antennae simultaneously, and since the transmission lines are of equal length, we have zero phase dii'erence and full addition of the two current-s in the receiver. For 0:30", the space wave will reach one antennaa quarter wave length before it reaches the other. Then the currents at the receiver will add in quadrature, Oiving an intensity 1.4'1 times that from either antenna alone. For 0:90", the

space wave will reach one :antenna a haltl wave length before the other, and the currents at the receiver will be in direct opposition, giving-zero reception. The intensities for 9:0, 30, and 90 are theregore in the ratio 2, 1.41 andO. For 0:150 we'again have quadrature addition, and an intensity 1.41 and for v(9:180", we have an intensity 2.00.

A single cardioid unit gives the following intensities:

Angle' Relative 9. Intensity. o I 1.00

9=90, two currents of intensity .50 inl direct opposition givingzero resultant in the receiver. I

product of the radii of A and B for the same 1 row. This sharpens the main lobe of the 4 for a broadside pair of static antennae a I half Wave length apart, and square or .cube all v into coincidence.- All of `the/ti'ansmission 0:150, two currents of intensity .066, in quadrature giving a resultant 1.41 .066: .093. l

0=1'80, no current from either antenna. Putting the above in tabular form Directive 0 curve for Cgighlgd Directive curve lor two static ung two cardioid units antennaev 0 2.00 1.00 2.0 X l.0=2.00 75 30 1.41 .933 1.41 X.933=1.31 0 50 0 X 50:0.0 .150 1.4! .006 1.41 X .066:.093 180 2.00 0 2.0X.00=.00

Fig. 4 shows the shape of the curve A for the two static antennae, the curve B of the cardioid unit, and the product or curve for the combination. In this,l curve A hasbeen reduced to the basis of unit intensity for `0:0.

A pair of spaced loops is another applica; tion of' the product principle. Two static 8 antennae spaced a quarter wave length apart in the direction of the signal, and with one transmission line a quarter wave length longer than the other, give a cardioid directive curve. With the static antennae replaced by loops pointed in the directiono'the signal, the system gives a directive curve which is the product of the cardioid just mentioned and the figure eight which is the directive K curve of a loop. The quarter wave length spacing of the-loops isnot essential, but is the simplest case to discuss.

A pair of broadside wave antennae. is an# other application. 'In this case the cardioid, corresponding to two units a quarter wave length apart in the direction of signal travel, is multiplied by the very sharp ligure eight curve of the broadside wave antenna.

The product principle may be extended to groupsof groups or rows of rows. Qne such application is of especial importance. In order to obtain a very sharp directive curve, using a broadside row of units, we extend thecurve, but smaller lobes appear Onthe sides as shown in Fig. 5.V It is evident that we might @tain a sharp mainA lobeI without any side lobes, if we could take the curve A Fig.

its radii. To lay out a system which will give a directive 'curve which is the square of A Fig. 4, we would needl to use two pairs' of unitsJ each pair of which would give A of Fig. 4 and then treat each of these pairs as a unitfof a big pair using the same spacing, as shown in Fig. 6. This puts the'center of the .second pair a half wave length from that of the rst pair, which brings two of the antennae lines have the Isame electrical'jlength, so a' single, unit at the -center giving double intensity may beV used in place of the two'. Thus l :2:1 groups just described into a. broadsideA pair spaced a half wave length center to center of group. This gives Group I 1:2:1 Group 1I 1:2:1

Total system 1:3:3:1

Again there are antennae coinciding, so that in effect we simply add an antenna. on one end of the row and increase the relative intensity of the two middle units to three times that of the end units. Such a system vgives the directive curve D of Fig. 10 which is the product of A of Figs. 4 and l0 and C of Fig. 10 or the cube of curve A of Figs. 4 and 10. Carrying the process one step further gives a broadside row of five antennae spaced a half wave length, and having intensities in the ratio 1 4:6 4: 1. This gives the directive curve E of Fig. 10, which is curve D of Fig. 10 multiplied by A of Fig. '10, or the square of curve C of Fig. 10. The product principle makes it a simple matter to calculate the directive curve of a eld covered with antenae in square formation for this may beconsidered as a broadside row of end-on ro'ws or vice versa. Y

In order to obtain advantage from changing the intensity of certain of the units in a multiplev unit receiving system, it 1s not necessary to adhere to the exact arrangement of values just described, changing the intensity of the units near the middle of a. broadside row as compared with that of the end units, is a means of altering the directions from which there is zero reception. For example, three units in a broadside row spaced a half wavelength apart, and with equal intensities give zero reception 42o from the normal signal direction (perpendicular to the row of units) Reducing the intensity of the middle unit brings the angle of zero reception closer to the signal direction butl permits stronger reception from directions nearly parallel to the row. If the intensity of the middle unit is reduced to Zero the angle of zero reception is 30o from the signal direction but the remaining units give full addition for disturbances coming at right angles to the signal or parallel to the row. On the other hand. if the intensity of the middle unit is greater than that of each of the end units the reception from a direction at right angles to the signal is reduced, and the angle of zero reception is more than 42 from the signal direction. reaching 90 when the intensity of the middle unit is twice that of either end unit. With other from the units farthest from the source of signals (or advancing the phase of the currents from these units) and increasing the electrical lengths of the lines from the units that are nearer the source of the desired signals. Thus in the case of a broadside pair, the transmission lines should have equal length to give maximruu reception for signals coming at 0:00 or right angles to the line connecting the two antennae, but to warp the curve 30 to the right (i. e. to obtain maximum reception for signals from the direction (2f-"30 right) we must lengthen the line from the right hand unit or shorten that from the left hand unit, or both so as tomake the difference in their electrical lengths equal to one half the distance between the units (sin 3 0:.5) How far the ywarping may be carried satisfactorily depends on the directive properties of the individual units, for obviouslyno adjustments of relative phase can secure good reception from directions for which the units themselves are ineiiicient. Therefore, if warping is to be carried very far, itis desirable to have the unit antennae also adjustable in order that their directions of maXi-' mum reception may be shifted at the same time. For example, if the antennae are loops and it is desired to carry warping more than about 30, it should be possible to turn the loops', or to obtain the equivalent effect by means of crossed loops and goniometers. 0r if the system consists of a broadside row of wave antennae and warping through a wide angle is necessary, it would be desirable to substitute for the Wave antennae end-on rows of static antennae or of crossed loops with goniometers.

The advantage gained by warping the directive curve of a multiple unit receiving system is not limited to increasing the signal in tensity from stations not located directly in line with the antenna system, but the warping may be used to prevent recept-ion of static or interference from certain directions. Most sharply directive systems have certain directions for which the reception is zero and if isturbances come from a definite direction they may frequently be eliminated by so adjusting the system as to cause one of these directions of zero reception tol coincide with the direction of the disturbance. The adjustments described above for warping, not only shift the direction of maximum reception but turbance suiciently to reduce the disturbance to negligible magnitude, while only slightly reducing the intensity of the desired signal. As an illustration of a complete receiving system adapted for multiplex reception in which the principles above set forth may be employed I have indicated in Fig. 1 three parallel wave antennae numbered 1, 2 and 3, each of which ma point in the general direction of the signa s which are to be received.

The ends B1, B1, B3 of these antennae are provided with the usual reflection transformers R1, R2, R3, to utilize the antenna wires as a transmission line to transmit to thereceiving station signals traveling in the direction from A1 to B1 or to transmit to the receiving station over the antennae as a transmission line desired balancing or neutralizing currents. At the ends A1 and A3 I have indicated transformers T1, T3 and S1, S3 for supplying signaling and compensating currents to the balanced transmission lines L1, L3 and M1, M3',

by means of which the desired currents are transmitted to the receiving station. By way of modification I have indicated in antenna No. 2 a reflection transformer R1fat end A2 and have provided transformers T1 and S2 connected at an intermediate point in the antenna to the transmission lines L2 and M1.

In the receivingstation there may be provided for each antenna artificial lines N1, N1, N3, O1, O1, O3 or,other time -or phase adjusting circuits to which the currentsconveyed over the transmission lines maybe supplied by transformers 4, 5, 6, 7, 8 and 9. To provide intensity adjustments the currents from the artificial lines are supplied through potentiometers 11, 12, 13, 14, 15, 16, to the control circuits of the coupling tubes l-S, l-N, 2-S, 2f-N, 3-S and 3-N.

The output circuits of these coupling tubes are connected in parallel to the primary of transformer 17, the secondary of which supplies signaling current to suitablytuned receiving circuits and receiving apparatus of any desired type. For testing and adjustingpurposes suit-able switching arrangements should be provldedto permit anyone or more of the plate circuits of the couplingtubes tol will be one whlch impresses the total availf supply current to the receiving apparatus to the exclusion of other tubes. It will be understood that the vacuum tubes indicated will be connected inthe usual manner, art of the connections having been omitte In adjusting the system descri ed to obtain the desired results the sllding connections- 18, 19, 20, 21, 22 and 23 and the inten'- from the drawing for the purpose'of sim lilication.`

sity couplers 11, 12, 13', 14, 15 and 16 are rst adj usted to give the best signal reception. This may be done by adjusting first with one antenna unit at a time connected to the receiving apparatus, then with two units and finally with all three units. In this way an adjustment may be made so thatthe signaling currents received upon the three antenna units will all add in phase in receiving apparatus and if the currents supplied by the different antennae are all ofthe same intensity the maximum signaling currents will be of threetimes the amplitude of the current supplied by single antenna units. The product principle whichv I have described above ap-.

plies o the system which I have described and sharper directivity in reception will be obtained than with a single unit. It may however, be found that when the system is thus adjusted for maximum intensity, interference will be present from a direction between 60, and 120 from that 'of the desired, signals; iVith certain antenna spacings this interference may be largelyeliminated by readjusting the intensity couplers so that the intensity of the currents received from -antenna 2 and impressed upon the receiving apparatus differs from that of the currents received and impressed upon the receiving ap- A paratus from antennae 1 and 3 respectively. While I have indicated in Fig. 1 the complete apparatus for receiving only one mes= sage. I have indicated additional potentiomete'rs or intensity couplers 24, 25, 26, 2,7, 28

and 29 and 31, 32, 33, 34:, 35, 36 with sliding contacts between the intensity couplers and' the artificial lines. These may be connected to additional sets of'coupling tubes and receiving apparatus so that as many different messages as desired all coming from the same direction or from different directions may be received from a single antenna system.

It will be noticed that in Fig. 1 the arrange- Ament for impressing signals coming in the direction from A1 to B1 on the control element of the coupling tube l-S is essentially the same as that by which signals coming in the direction from B1 to A1 are impressed on the control element of-coupling tube 1-N. For the present the discussion will be`conlinedto antenna No. 1, the coupling tubes 2-S, 2N, 3-S and 3-N being considered inactive.

'If the desired signal has the vdirection A1 to B1, it will be received almost entirely through the coupling tube 1-`S,l and the desirabley adjustment of the potentiometer 11 able potential on the control element of the coupling tube l-S. If at the Sametime there is a disturbance coming in the v direction B1-'1-A1, this impresses a relatively small voltage on the 'potentiometer 11 and a much larger voltage on the potentiometer-14. But by adjusting .potentiometer 14 'so that only a fraction of the available voltage across the lll) potentiometer is impressed upon the coupling tube control element, the voltage supplied to the control element of coupling tube 1--N due to the disturbance, may be made equal to the voltage which the same disturbance causes to be impressed on the control element of coupling tube 1-S. The voltages impressed on the control elements of coupling tubes 1-S and l-N as a result of the disturbance, may then be brought into phase opposition by adjustment of the sliding contact 21 on the artificial line O1. All effect of the disturbance coming in the direction BI---A1 will then disappear from the receiving set, Since the voltages impressed on the control elements of 1--S and l-N are equal and opposite and the signal frequency anode currents will neutralize. The desired signal causes only a relatively small voltage to be impressed on the potentiometer 14 and since only a small fraction of this voltage is applied to the control element of the coupling tube 1--N, there is practically none ot the desired signal current in the anode circuit of control tube l-N, and the adjustment of potentiometer 14 and phase adjustment 21, do not impair the strength of the desired signal which is supplied to the receiving set through coupling tube l-S.

It is evident from the symmetrical arrangement, that b means of a different set of adjustments o the potentiometers 11 and 14 and of the sliding contacts 18 and 21 which adjust phase, the receiving set may be made to receive with full intensity desired signals coming in the direction B1-A1, while undesired signals or disturbances coming in the direction Al-Bl, are neutralized in the receiving set. In other words the unidirectional properties of the antenna may be reversed. Since the system shown in Fig. 1 provides for a number of receiving sets, and the adjustments of these sets are mutually independent, it is possible to obtain unidirectional reception with one receiving set, for signals coming in the direction Al--BJL and at the same time to receive signals coming in the direction Bl-Al, on another re ceiving set, to the exclusion of signals or disturbances coming in the direction Al-BP The same is true of the entire system of three antannae, since each antenna can be adjusted in the same way.

If one of the signals to be received on the multiplex system shown in Fig. 1 comes from such an angle that the signal Wave does not reach the three antennae simultaneously, it will usually be desirable to warp the system, thereby giving it a directive curve which points toward the desired sending station. If for example the desired signal reaches antenna No. 3 first and is to be received by receivingset No. 1, the warping will be accomplished by retarding the phase of the voltages received from antenna No. 3 by moving the sliding contacts 20 and 23 to the right, and advancing the phase of the voltages received from antenna. No.y 1 by moving the contacts I18 and 21 to the left. In this manner the compensation or unidirectional adjustment of each antenna taken by itself may be kept the same but the phase of the signal currents in the receiving set from the three antemiae may be brought into coincidence thus giving full signal addition. This warpingV of the directive properties ofthe system for receiving a particular station on receivingset No. 1,.has no eect on the adjustments for the remaining sets. YThus it is possible at `the same time to be receiving on set No. 2 another station which calls for warping in the other direction, or advancing the phase of the voltages received from antenna No. 'and retarding the phase'of the voltages received from antenna No. 1, While sets No. 3 and N o. 4 may be usingthe system unwarped.

Warping may be used either to increase the signal intensity from stations not directly in line with the system, or it may be used to reduce interference or static coming from certain quarters.

By a modification of the arrangement shown in Fig. 1, the adjustments for warping, and for weighting the antennae or varying their relative intensities can be performed without disturbing the unidirectional adjustments of the individual antennae. This modilication consists in combining the anode currents of coupling tubes l--S andV l-N directly as in Fig. 1 and similarly combining the anode currents of 2-S and 2-N, and of 3--S and 3N, thus producing three currents each from an adjusted antenna, and then combining these three currents through devices by which their vrelative phase' and intensity can be adjusted. l

In Fig. 2 I have indicated a slight modilll() ication of the system shown in Fig. 1 consisting in the use f variable coupling transormers 40 and 41 which may be moved along the artificial lines to adjust the phase and moved closer or farther from the lines to adjust the intensity of the currents impressed upon the input circuits of the coupling tubes.

In Fig. 1, I have shown a broadside receiving system consisting of three Wave antenn. Fig. 7 shows a broadside receiving system consisting vof three static antennae and three loops with transmission lines leading to the receiving station where the current from each loop may becombined with that from the corresponding static antenna in such a Way as to form a Yunidirectional unit. The currents from the three unidirectional units may then be combined `to obtain the sharp directive propertiesl characteristic of the broadside row. Fig. 8 shows a similar arrangement in which each of the three unidirectional units is obtained by combining two static antennae spaced an appreciable fraction of a wave length apart inthe direction of signal propagation. Fig. 9 shows an arrangement similar to that of Fig. 8 except that the staticantennae of Fig. 8 are replaced by loops, the loops having the advantage of immunity from disturbances coming from the side. With stationary loops the arrangement shown in Fig. 9 .cannot be warped as far to the side as 'that shown in Fig. 8, because the loops themselves-are directive. If, however, the loops are so constructed that they can be turned so as to point in any desired direction, then Fig.9 permits as much freedom in warping as Fig. 48 while at the same time. giving higherl directivity. In-

stead of turning the loops in .the field, the

same result can be ?obtained by means of crossed loops and goniometers of the Bellini Tosi type. The gonometers may be locate-d in the receiving station if a separate transmission line is provided from each loop.

While I have shown antenna systems made up of certain types of directional units arranged in broadside rows it will be understood in accordance with the principles set forth that any other form of directional unit may equally well be employedA and that as many units as desired may be used without-departing from the scope `of my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is: 1. The combination in a radio receiving system of three or more parallel'unidirectional receiving antennae, each having a length ferent antennae so as to impress upon the receiving apparatus currents of different :intensity from the intermediate antenna or antennae than from the outside antennae.

2. The combination in a radio receiving system of three or more parallel horizontal antennae separated from one another by a substantial fraction of a wave length of the signals to be received; each having a length.

as great as a wave length ofthe signal to be received, a receiving appara-tus, means for combining the currents received *upon the different antennae in the receiving apparatus and means for varying the lntenslty and phase v of the' currents impressed upon the receiving apparatus from the different antennae so' as to impress upon the receiving apparatus currents'of different intensity andA phase from the intermediate antenna o r antennae than from the outside antennae in such a manne;l

3. The 'method of operating a radio re ceiving system comprising a plurality of directive receiving units and a plurality of receiving sets which consists in selecting from each of sald receivmg umts and impressing upon one of the receiving sets a current of a desired phase and intensity and simultaneously selecting from each of said receiving units and impressing upon another of said receiving sets a currentreceived from a'dlfferent source having a dierent carrier fre-' quency than tliat of the first mentioned current.

4. The method of operating a radio receiving system comprising a plurality of directive receiving units an a plurality of receiving sets which consists in independently selecting from each receiving unit a plurality of 'currents derived from different sources having different carrier frequencies, combining in each receiving set the currents from a single source which have been selected from the different receiving units and adjusting the phases of the combined currents to produce the desired signal reception.

5. The method of-operating a radio receiving system comprising a plurality of directive receiving units and aplurality o f receiving sets -which consists in independently selecting so v from each receiving unit a plurality of currents derived from different sources having different carrier frequencies, combining in each receiving set the currents from' a single source which have been selected from the different receiving units andv adjusting the phases and intensities of thecombined currents to produce reception of the desired signal and eliminate interference from Waves arriving from other directionsthan that of the desired signal.

6. The combination in a radio receiving system of a plurality of directive receiving units, a plurality of sets of receiving apparatus, means for -impressing upon each receiving apparatus currents derived from each of thereceiving units and independent means Vassociated with each receiving unit for separately adjusting the phase andintensity of. the diiferent currents impressed therefrom upon the different receiving sets.

7. `The combination in a radio receiving system of a plurality of directive receiving A units, a plurality of sets of receiving appara',- tus, an artificial line associated with each receiving unit, means associated with each artiv ficiail line Vfor simultaneously selecting a plurality of currents derived from different 4'transmitting sources, 4means for impressing upon each receiving s'et currents derived from a single transmitting source andselected from the different -receiving ,units'and'means for.

` adjusting the'phase andA intensity ofthe currents thus impressed upon each receiving set.

8. The combination in a radio receiving system of a plurality of directive receiving units, a receiving set and means for impressing upon the receiving set currents derived from the different receiving units, said means comprising a plurality of coupling tubes having their output circuits connected in parallel and associated with the receiving sets and their control circuits connected individuallyto the different receiving units.

9. The combination in a radio receiving system of a plurality of directive receiving units, a receiving set and means for impressing upon the receiving set currents derived from the cliifereiit receiving units, said means comprising a plurality ot coupling tubes having their output circuits connected in parallel and associated With the receiving sets and their control circuits connected individually to the different receiving units, the control circuits of some ofthe tubes having impressed thereon desired signaling currents and the .control circuits of other tubes having impressed thereon currents ot' the proper phase and intensity to eliminate interference with the desired reception.

l0. The combination in a radio directive receiving system of a plurality ot' rows of receiving antennae each row consisting of a plurality of units separated from each other in the direction of desired signals by a substantial fraction of a wave length and said rows being separated from each other in a direction substantially ati-ight angles to the signal direction by a substantial fraction of a wave length of the signals to be received, a receiving apparatus7 balanced transmission lines connecting each antenna unit with the receiving apparatus, and means at the receiving apparatus for adjusting the phase and intensity of the currents impressed from each transmission line upon the receiving apparatus.

1l. The combination in a radio receiving system of a row of more than two directive receiving' units separated from one another by a substantial fraction of a wave length, means for changing the directive curve of each of said units and transmission lines connecting each of said units to a receiving station.

12. The combination in a radio receiving system of a plurality of rows of directive receiving units, the rows being separated from r changing the directive curve of each unit and transmission lines connecting each of said units to a receiving station.

14. The combination in a radio receiving system of a plurality of rows of directive receiving units, the rows being separated from one another by a substantial fraction of a wave length, means for changing the directive curve of each unit, transmission lines connecting each of said units to a receiving station, and means at a receiving station for separately selecting from each unit a plurality of different currents of a desired phase and intensity and impressing the currents so selected upon a corresponding number of sets of receiving apparatus.

l5. The combination 1n a radio receiving system of a plurality of directive receiving units, a receiving set, a pair of artificial lines associated with each receiving vunit and means for impressing upon thereceiving set currents derived from all of said artificial lines. A

16. The combination in a radio receiving system of a plurality of directive receiving units, a receiving set, a pair of articial lines associated with each receiving unit, a series of coupling tubes equaling in number the total number of artificial lines, the output circuits of said tubes being connected in parallel and associatedwith the receiving set, and individual connections from each of said artificial lines to the control circuit of a coupling tube.

In witness whereof, I have hereunto set my hand this 20th day of November 1922. EDWARD W. KELLOGG. 

